The present invention relates to a chemical mechanical polishing method. More particularly, the invention relates to a chemical mechanical polishing method capable of efficiently removing an unnecessary wiring material and providing a high-quality polished surface when manufacturing a semiconductor device using copper or a copper alloy as the wiring material.
In recent years, a further increase in the degree of integration has been demanded for a semiconductor device, and scaling down of wirings formed in a semiconductor device has progressed. A damascene method has attracted attention as a technology capable of achieving further scaling down of wirings of a semiconductor device. In the damascene method, a desired wiring is formed by filling a groove formed in an insulating material with a metal material which forms a wiring and removing an unnecessary wiring material by chemical mechanical polishing. In the damascene method, a high polishing rate is required from the viewpoint of an increase in efficiency and throughput of the polishing step.
A wiring may be polished excessively when forming a damascene wiring, whereby the wiring may have a concave shape. Such a concave wiring shape is called “dishing” or “erosion” and results in a decrease in the yield of semiconductor devices. A surface defect called a “scratch” may also occur during polishing and result in a decrease in the yield of semiconductor devices.
There may be a case where abrasives remaining on the wiring or foreign matter remaining on the insulating film causes a problem after the chemical mechanical polishing step. Or, a phenomenon called “corrosion” in which the wiring is corroded may also occur. This also significantly affects the yield of semiconductor devices.
Various chemical mechanical polishing aqueous dispersions have been proposed in order to reduce occurrence of dishing or erosion to improve the planarity of the polished surface or to reduce occurrence of a scratch or corrosion.
For example, JP-A-10-163141 discloses that a composition containing abrasives, water, and an iron compound has an effect of reducing occurrence of dishing. JP-A-2000-160141 discloses that a composition containing abrasives, a-alanine, hydrogen peroxide, and water is effective for reducing occurrence of dishing and erosion to provide a polished surface exhibiting excellent planarity. JP-A-10-44047 discloses that the planarity of the polished surface is improved by adding a surfactant to a chemical mechanical polishing aqueous dispersion.
In the chemical mechanical polishing step, a high polishing rate is required in addition to improving the planarity of the polished surface and reducing occurrence of surface defects. However, few studies have been conducted on a chemical mechanical polishing aqueous dispersion which can achieve these requirements in combination.